Increased neutrophil priming and sensitization before commencing cardiopulmonary bypass in cardiac surgical patients

Background. Neutrophil activation is implicated in postoperative complications in patients having cardiac surgery with cardiopulmonary bypass (CPB). This study was designed to determine the temporal fluctuations in the primability of neutrophils in the preoperative, intraoperative, and postoperative periods of CPB, and specifically whether CPB was a primary cause leading to increased neutrophil priming and elastase release. Methods. Twenty patients undergoing multiple coronary bypass grafting, valve replacement, or both of these procedures were included in this study. Blood samples were taken 1 day before the operation and at several time points during and after the operation. For each sample, blood was divided in vitro into four subgroups: control without priming, priming alone with cytochalasin B (CytoB), priming plus stimulation with platelet-activating factor (PAF), and priming plus stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP). The elastase concentration of all these samples was determined using the enzyme immunoassay. Results. Compared with the controls, CytoB priming increased release of elastase more than 10-fold before CPB, 1.6-fold during CPB, and 1.5-fold at the end of CPB. Further stimulation with PAF or fMLP showed greater increase of elastase than priming alone, with peak values in both found before CPB. This increased neutrophil primability prior to CPB did not differ significantly among patients who had different preoperative disease profiles. Conclusions. Our data suggest that neutrophil priming occurs early before commencing CPB in cardiac surgical patients, and that CPB is not the primary primer. Anesthesia, surgical trauma, and other events may have been involved in neutrophil priming and sensitization before CPB, which warrants further investigation.